Learning from clinical phenotypes: Low-dose biophotonics therapies in oral diseases.

This narrative review on the use of biophotonics therapies for management of oral diseases is written as a tribute to Prof. Crispian Scully. His seminal contributions to the field are highlighted by the detailed, comprehensive description of clinical presentations of oral diseases. This has enabled a more thorough, fundamental understanding of many of these pathologies by research from his group as well as inspired mechanistic investigations in many groups globally. In the same vein, a major emphasis of this narrative review is to focus on the evidence from human case reports rather than in vitro or in vivo animal studies that showcases the growing and broad impact of biophotonics therapies. The similarities and differences between two distinct forms of low-dose biophotonics treatments namely photodynamic therapy and photobiomodulation therapy are discussed. As evident in this review, a majority of these reports provide promising evidence for their clinical efficacy. However, a lack of adequate technical details, precise biological rationale, and limited outcome measures limits the current utility of these treatments. Future investigations should attempt to address these shortcomings and develop better designed, rigorous, controlled studies to fully harness the tremendous potential of low-dose biophotonics therapies.

Photodynamic inactivation of normal and antifungal resistant Candida species.

BACKGROUND: Susceptibility of bacterial and fungal species to the photodynamic killing effects of various photosensitizing dyes has received increasing attention. In the oral cavity oral candidiasis is primarily caused by Candida albicans. Evidence suggests that Oropharyngeal Candidiasis, found frequently in patients with immunodeficiency, present with mixed Candida organisms and are more difficult to treat than those solely due to C. albicans. In the present study we demonstrate the ability to efficiently kill antifungal resistant isolates of Candida using Photofrin induced PDT. METHODS: Candida strains from the ATCC as well as fluconazole and amphotericin B resistant and sensitive isolates from adults with AIDS were grown cultures and grown under standard conditions. Photofrin was added to appropriate cultures as dictated by experimental design. Light was delivered to assigned cultures using a 630 nm laser source at a power density of 150 mW/cm(2), for appropriate time to deliver 45-135 J/cm(2). Colony forming assays were used to determine survival. RESULTS: After illumination cultures treated with Photofrin had significant reduction in colony forming ability at all light doses examined. Isolates from AIDS patients which had demonstrated antifungal resistance showed equivalent sensitivity to photodynamic killing as did control ATCC cultures of the same strain. CONCLUSION: This study demonstrates Photofrin induced PDT can eliminate Candida species with significant efficiency as revealed by colony forming ability. Further Candida isolates from AIDS patients that had demonstrated fluconazole and amphotericin B resistance were equally susceptible to photodynamic killing.

The use of photodynamic therapy using 630nm laser light and porfimer sodium for the treatment of oral squamous cell carcinoma.

PDT has been demonstrated in clinical studies to be an efficacious method for the treatment of dysplastic, microinvasive and early forms of cancer. The advantage of PDT for early carcinomas of the oral cavity is the ability to preserve normal tissues while effectively treating cancers up to 1cm in depth. The case presented here successfully demonstrates the ability to use PDT to treat maxillary gingival squamous cell carcinoma thereby sparing the use of surgery or radiation therapy at this point in the management of the disease.

Photodynamic therapy for chest wall recurrence from breast cancer.

Breast cancer is common with over 230,000 new cases diagnosed each year in North America alone. While great strides have been made to achieve excellent cancer control and survival, a significant minority of patients fail locally. While initial salvage to regain disease control is of the utmost importance, it is not universally successful. This leads to a therapeutic quagmire. Additional surgery, radiation and chemo-hormonal therapy are possible, but they are usually highly morbid with low success rates. Photodynamic therapy appears to be an underutilized salvage modality for this unfortunate patient population. This report analyzes and reviews the role of photodynamic therapy for patients with chest wall re-recurrence from breast cancer.

Effect of photodynamic therapy on revascularization of fasciocutaneous flaps.

OBJECTIVE: Photodynamic therapy (PDT) may be used as an adjuvant intraoperative treatment to improve locoregional control. PDT has been shown both to delay wound healing and to have a deleterious effect on flap survival after a primary ischemic insult. This delay in wound healing may make the flap dependent on its pedicled blood supply for a prolonged period. Long-term flap loss may be experienced. The effect of PDT on flap revascularization, with subsequent dependence on its vascular pedicle, is evaluated. STUDY DESIGN: Randomized controlled trial using a rodent model. METHODS: A rat fasciocutaneous flap was used. Study groups were as follows: group I received no treatment; group II received treatment with 630-nm light; groups IH and IV were given Photofrin (in group III, loupes without a fiberoptic light source were used for flap elevation, and in group IV, light source was employed); and group V was given Photofrin and 630-nm light. Primary ischemic times of 2 or 4 hours were used. Vascular pedicles were ligated on postoperative day (POD) 5, 6, or 7, and percentage of flap survival was evaluated 7 days later. RESULTS: With 2 hours of ischemia, revascularization was decreased in the PDT group on POD 6 (P < .05) and on day 7 (P < .005) when compared with the other groups. With 4 hours of ischemia, revascularization was decreased in the PDT group on PODs 5 (P < .001), 6 (P < .01), and 7 (P < .005). CONCLUSION: Intraoperative PDT decreases revascularization of a rat fasciocutaneous flap.

Photofrin photodynamic therapy for treatment of AIDS-related cutaneous Kaposi's sarcoma.

OBJECTIVE: Kaposi's sarcoma, the most common malignancy in AIDS patients, often presents with painful cutaneous lesions that are difficult to treat effectively despite a wide variety of therapeutic approaches. We used photodynamic therapy in an attempt to provide effective palliative treatment for this disease. METHODS: Photodynamic therapy utilizes the activation by light of a photosensitizing drug that preferentially accumulates in tumor tissue such as Kaposi's sarcoma. We enrolled 25 patients who received 1.0 mg/kg of Photofrin 48 h before exposure to 100-400 J/cm2 of 630 nm light. RESULTS: Of the 348 lesions treated, 289 were evaluable: 32.5% had complete clinical response, 63.3% had partial clinical response and 4.2% were clinical failures. There was a strong correlation between response and light dose: 54% of lesions achieved a complete clinical response at optimum light dose (> 250 J/cm2). There was no correlation of response with CD4 cell count nor was there a change in CD4 cell count post-treatment. At 400 J/cm2 full field scabbing and necrosis occurred in 90% of the treated fields. Thus, the maximum tolerated dose was determined to be 300 J/cm2. At light doses of 250 J/cm2 and below the toxicities were limited to erythema and edema in the treatment field. Forty-three biopsies were taken 0.5 h to 4 months post-treatment. These showed little change in the B and T cell infiltrates identified. Kaposi's sarcoma cells disappeared post-treatment in certain lesions. CONCLUSION: Photofrin is effective palliative treatment for HIV-associated Kaposi's sarcoma.

Effect of photodynamic therapy on the critical primary ischemic time of fasciocutaneous flaps.

BACKGROUND: Photodynamic therapy (PDT) may be used as an adjuvant intraoperative therapy to improve locoregional control. PDT has been shown to delay wound healing. This raises concern about PDTs effect on survival of fasciocutaneous flaps. OBJECTIVE: Evaluate the effect of 1) PDT on the critical ischemic time in a rat fasciocutaneous flap model and 2) photosensitizer activation by the surgical light source. DESIGN: A fasciocutaneous flap, based on the left inferior epigastric vessels, was used. Ischemic times of 2, 4, 6, 8, 10, and 12 hours were induced by clamping the vascular pedicle. Animals were randomly divided into five groups: ischemia only, group I; light treatment to wound bed, group II; Photofrin before surgery with the flap elevated without a fiber optic head light, group III, or with a headlight, group IV; Photofrin prior to surgery with light treatment to the wound bed, group V. Flap survival was assessed on postoperative day 7. RESULTS: The critical primary ischemic time of group V (PDT) was significantly less (P < .05) than groups I, II, III, and IV. There was no statistical difference in the critical primary ischemic time when a fiber optic headlight was used (group III vs. group IV). CONCLUSION: Intraoperative PDT significantly reduces the critical primary ischemic time of the rat fasciocutaneous flap. White light illumination of the operative field does not result in photosensitizer activation and has no effect on the critical primary ischemic time.

A phase II/III clinical study of tin ethyl etiopurpurin (Purlytin)-induced photodynamic therapy for the treatment of recurrent cutaneous metastatic breast cancer.

BACKGROUND: Chest wall recurrence of breast cancer after mastectomy, radiation therapy, and chemotherapy poses a therapeutic dilemma. Further intervention with any or all of these modalities is often futile and morbid. Left untreated, severe pain, infection, and suffering occur. OBJECTIVE: To ascertain whether photodynamic therapy may present a palliative option for these individuals. METHODS: A total of 86 lesions (2.4-cm mean diameter) were treated on eight patients who had biopsy-proven chest wall recurrence despite surgery, chemotherapy, and radiation therapy. Each patient underwent a single photodynamic therapy session in which 1.2 mg/kg of the drug tin ethyl etiopurpurin (Purlytin) was injected and followed 24 hours later by laser light treatment at 660 +/- 3 nm (at 150 mW/cm2 for a total light dose of 200 J/cm2). RESULTS: With a minimum 6-month follow-up, the objective response rates after photodynamic therapy were complete response, 92%; partial response, 8%; and no response, 0%. Lesions less than 0.5 cm had a 100% complete response. Morbidity was minimal with no systemic toxicity. One patient had a wound infection that responded to oral antibiotics. No photosensitivity reactions were reported in this set of patients. Posttreatment pain was reported and could be treated with medication and application of cold compresses. CONCLUSIONS: Photodynamic therapy offers an excellent local control rate of chest wall recurrence with minimal morbidity after multimodality treatment failure. The treatment is given in a single session and on an outpatient basis. In patients who may register a partial response or have recurrence or the incidence of further chest wall nodules after photodynamic therapy, the treatment is repeatable.

Photodynamic therapy for the treatment of nonmelanomatous cutaneous malignancies.

Photodynamic therapy (PDT) is a modality whose concept is not new to dermatologists. PDT has gained regulatory approval in the United States for the treatment of esophageal and lung malignancies. The field has grown over the last decade, and now phase II/III clinical trials using second generation drugs for the treatment of nonmelanoma skin cancers, palliation of metastases to the skin, and Kaposi's sarcomas have been introduced. These new sensitizers tend to reduce the one side effect of PDT, namely persistent generalized cutaneous photosensitivity. PDT has shown efficacy in (1) patients who have failed conventional therapies, and for whom local treatment options are limited (2) patients in whom surgery would result in cosmetic disfigurement, and (3) patients prone to developing multiple lesions as in Gorlins syndrome. Dosimetry is based on well-understood treatment matrices that have optimized light delivery with known photosensitizer administrations. The advantages of PDT for cutaneous malignancies include the ability to treat numerous lesions in one setting, in a noninvasive manner without any apparent concern for the development of carcinogenicity.

Photodynamic therapy for premalignant lesions in DMBA-treated hamsters: a preliminary study.

PURPOSE: Photodynamic therapy (PDT) involves the selective destruction of neoplastic cells through the activation of a photosensitizer by light. We have previously shown that the photosensitizer Photofrin (porfimer sodium) is selectively accumulated in transformed lesions destined to become malignant, but not yet definable histologically as precancers. The aim of this investigation was to determine if this premalignant tissue could be selectively destroyed by systemically administered Photofrin activated by 630 nm red light via an argon dye laser. MATERIALS AND METHODS: The carcinogenic model used was the DMBA (9, 10 dimethyl 1,2 benzanthracene)-treated hamster cheek pouch. The animals were treated with 0.5% DMBA in acetone thrice weekly for 6 weeks (experiment I, premalignant lesions), or 12 weeks (experiment II, malignant lesions). Ten animals were in experiment I; nine animals were in experiment II. These were divided into experimental and control subgroups. The 6-week experimental group received PDT and CO2 laser incision into the DMBA-treated area. The CO2 laser was used as a promoter of neoplasia in a field that had already undergone initiation from the DMBA treatment. The control groups received either CO2 laser incision alone into the DMBA-treated field or CO2 laser incision and argon pumped dye laser treatment (without Photofrin). The 12-week experimental group received PDT after CO2 laser excision of tumors. The controls received CO2 excision alone, or CO2 excision combined with postoperative hyperthermia. RESULTS: One hundred percent (three of three) of cheeks in experiment I receiving PDT developed necrosis of the treated area within 24 to 48 hours, but 0% (0 of three) subsequently developed tumors. No necrosis was seen in control cheeks receiving Photofrin without irradiation (0 of four) or irradiation without Photofrin (0 of six), and 56% (five of nine) of cheeks exposed to identical carcinogenic stimulus, without PDT, developed tumors (n = 9). In experiment II, 0% (0 of six) of cheeks receiving postoperative PDT developed tumor recurrence. In experiment II controls, 50% (three of six) of cheeks that underwent excision and hyperthermia developed tumor recurrence. In cheeks treated only with CO2 laser excision of tumors, a recurrence rate of 67% (four of six) was noted. These results were found to be statistically significant by the Student t-test on the binomial distribution (P < .01). One animal was treated with DMBA for 6 weeks, administered Photofrin, and the right cheek was irradiated and the animal was left for 30 weeks. The irradiated cheek epithelium necrosed but no cancer developed, whereas the positive control cheek developed a large cancer. CONCLUSION: These results suggest that photodynamic therapy possesses significant potential in elimination of premalignant tissue. This could be beneficial in treating potentially premalignant lesions such as oral leukoplakia, and useful as adjunctive therapy in removal of areas of field cancerization adjacent to surgical sites.

Photodynamic therapy and hyperthermia as an adjuvant modality in preventing tumor recurrence.

BACKGROUND AND OBJECTIVE: The objective of this study was to determine the relative efficacy in preventing tumor recurrence by photodynamic therapy (PDT), and by ablative CO2 laser surgery followed by PDT, compared to ablative surgery alone (negative control) or ablative surgery followed by a course of hyperthermia (positive control). STUDY DESIGN/MATERIALS AND METHODS: The cheek pouches of 36 hamsters were treated with 0.5% 9,10 dimethyl-1,2-benzanthracene in acetone three times a week. After 12 weeks all animals showed tumors of their cheek pouches and were divided into four groups. In groups number I, II, and III, all visible tumors were removed by aid of a CO2 laser. Animals of group I did not receive any further treatment. After tumor resection, the cheek pouches in group II were treated with hyperthermia by aid of a Nd:YAG laser and a temperature of 43 degrees C for 30 minutes. In group III after resection of the tumors, the cheek pouches were treated with PDT (75mW/cm2 175J/cm2--3mg/kg Photofrin i.p./24h). In group IV, the tumors were not excised, instead they were only treated with PDT (as above). All animals were observed for 50 days for any signs of tumor recurrence. RESULTS: In group I (CO2) all tumors (100%) recurred within 50 days. In group II (CO2 + hyperthermia) 61%, in group III (CO2 + PDT) 27.7%, and in group IV (PDT) 50% of all tumors recurred. The first signs of recurrence could be seen in group I, followed by groups II and IV. Group III was the last one presenting tumor recurrence. CONCLUSIONS: The combination of CO2 surgery and PDT produced significantly better results than CO2 surgery or PDT alone, and better than the combination of CO2 surgery and hyperthermia.

Bombesin antagonist prevents CO2 laser-induced promotion of oral cancer.

We previously reported that CO2 laser incisions in carcinogen-initiated fields promoted cancer development and caused release of growth factors. Here we examined the quantitative and additive properties of this tumor-promoting event and examined whether this promotion could be nullified by treatment with a bombesin antagonist, which down-regulates epidermal growth factor receptors. The model used for cancer promotion was the hamster buccal cheek pouch that had been treated with a carcinogen (9,10-dimethyl-1,2-benzanthracene) for 6 weeks, producing premalignant lesions. These lesions would evolve into a cancer eventually without further treatment. Promotion was measured both by increased fluorescence in response to systemically administered Photofrin, measured noninvasively using an in vivo fluorescence photometer, and by the timing of appearance of clinical tumors. Laser incisions (0-3) were made into the hamster cheek 1 week apart, or three incisions were done 1 day apart. Another group of animals received bombesin antagonist RC-3095 for 4 weeks during the time incisions were made, again measuring promotion. Laser incisions 1 week apart produced additive promotion, whereas three incisions 1 day apart were not statistically different from the group receiving only one incision. RC-3095 treatment completely eliminated the promoting effects of incision and totally stopped promotion for the 4-week period of treatment. After discontinuing treatment with RC-3095, lesion progression resumed at the untreated control rate. This work confirms that the promoting event of a laser incision follows a comparable time course to release of growth factors after such an incision and that it can be eliminated by treatment with bombesin antagonists.

Effect of photodynamic therapy on the healing of a rat skin flap and its implication for head and neck reconstructive surgery.

BACKGROUND AND OBJECTIVE: Photodynamic therapy (PDT) may as adjuvant therapy by used to reduce tumor recurrence in the head and neck with surgery, given intraoperatively after resection. A concern with the use of intraoperative PDT is the possible effect on wound healing, especially on the healing of myocutaneous skin flaps, which are widely used to reconstruct defects following resections for head and neck cancer. STUDY DESIGN/ MATERIALS AND METHODS: A flap, based on the inferior epigastric artery, was prepared in thirty male Lewis rats. Group I did not receive any further treatment but the wound was left open for 20 minutes. Group II was injected with 5mg/kg Photofrin, 48 hours prior to the operation and also did not receive any further treatment. The wound bed and wound borders of group III were treated with 630nm light of different dosages, delivered by an argon dye laser. Animals in group IV received 5mg/kg Photofrin 48 hours prior to the operation and their wound beds were treated with the same light dosages as group III. After the treatment all flaps were replaced into the wound bed and the incisions were closed. Biopsies for histological analysis were taken at several time points; and on day 21, biopsies for wound tensile strength measurements were taken. RESULTS: The wound healing in group I, II, and III appeared normal and there were no differences seen between these groups. Also, the tensile strength did not differ significantly. The flaps of group IV showed serous effusion, epidermal necrosis, and weaker tensile strength (P = .04 and .02 for the light doses of 50 J/sq cm and 75 J/sq cm respectively) at a specific time point. CONCLUSION: The results of this study demonstrate that PDT given immediately before flap reconstruction will result in delayed wound healing. These results should be considered when contemplating the use of PDT as adjuvant intraoperative therapy for tumor surgery requiring flap reconstruction after ablative surgery.

Localization and treatment of transformed tissues using the photodynamic sensitizer 2-[1-hexyloxyethyl]-2-devinyl pyropheophorbide-a.

BACKGROUND AND OBJECTIVE: Photofrin is the photosensitizer currently used in most clinical trials examining the efficacy of photodynamic therapy (PDT) for the treatment and/or palliation of neoplasia. Although this drug has been shown to be efficacious in many of these trials, it possesses less than ideal qualities for use in a systemically administered photosensitizer. A new photosensitizer, 2-[l-hexyloxyethyl]-2-devinyl pyropheophorbide-a (HPPH), was developed for PDT. HPPH possesses more rapid clearance from skin and greater cytotoxicity per drug dose than Photofrin. The aims of this study were to: (1) examine the uptake and retention of HPPH in tissues undergoing malignant transformation using laser-induced fluorescence, and (2) evaluate the efficacy of HPPH and 665 nm light in treating carcinogen-induced tumors of the hamster buccal cheek pouch. STUDY DESIGN/MATERIALS AND METHODS: The model of tissue transformation was the carcinogen (9,10-dimethyl-1, 2-benzanthracene)-induced premalignant and malignant lesions of the hamster buccal cheek pouch. Following induction of the specific transformation stages, hamsters were injected intraperitoneally with 0.5 mg/kg HPPH. Subsequently, the buccal mucosa was examined for fluorescence at various times up to 72 hours after photosensitizer injection. RESULTS: Uptake studies of HPPH showed highest fluorescence levels in tissues 48 hours after HPPH injection. Fluorescence levels of tissues increased significantly as follows. Normal < dysplasia < papillomas < squamous cell carcinomas. Carcinogen-induced tumors in 14 hamsters were treated with surface illuminations of red light (665 nm) via fiber optics coupled to an argon-ion pumped dye laser 48 hours after intraperitoneal injection with either 0.5 or 1.0 mg/kg HPPH. Complete necrosis of tumor tissues 7 days following PDT was observed in 57% (4/7) with 0.5 mg/kg and 86% (6/7) with 1.0 mg/kg HPPH.

Lack of reciprocity in drug and light dose dependence of photodynamic therapy of pancreatic adenocarcinoma in vitro.

Two human pancreatic cell lines, MIA PaCa 2 and Capan 2, were treated by photodynamic therapy in vitro with Photophrin (0.01-25 micrograms/ml; 24 h) and then light (1-50 J/cm2; lambda = 630 nm). The following model was fit to 6 datasets with weighted nonlinear regression: [sequence: see text] The symbols are: E, cell growth; Econ, control growth in the absence of the combination; B, background signal; m, slope parameter; gamma, interaction parameter; D, concentration of Photofrin; L, light dose; F, fraction of Photofrin not photobleached by the light dose; k, k1, k2, bleaching parameters; A, distribution parameter for biexponential bleaching equation. Simple reciprocity of photosensitizer concentration and light dose was not found; compensation for photobleaching was critical. MIA PaCa2 required the monoexponential bleaching factor, whereas Capan 2 required the biexponential bleaching factor. The greater photosensitivity of MIA PaCa2 over Capan 2 can be best explained not by differences in the interaction parameter but rather by differences in the photobleaching pattern and rate. It may be possible to further enhance the selectivity of photodynamic therapy if differences in photobleaching between different cell types can be exploited by adequate dosimetry.

Evaluating the role of photodynamic therapy in the management of pancreatic cancer.

BACKGROUND AND OBJECTIVE: Cancer of the pancreas constitutes one of the major causes of cancer related death throughout the world. A 5-year survival rate of only 2% and a maximum of 20 months median survival in multi modality treatment studies dealing with the most favorable patients only, has been demonstrated. This review analyzes the principal treatments and available experimental data in view of a clinical application of photodynamic therapy (PDT) for the treatment of pancreatic cancer. STUDY DESIGN/MATERIALS AND METHODS: On the basis of published results, we examined the palliation of pancreatic cancer by chemotherapy alone; radiation alone and multimodality schedules (radiation and chemotherapy). Radical tumor resection was examined as attempted curative treatment. RESULTS: In reported therapeutic procedures, palliative or potentially curative, median survival was below 2 years. The GTSG reported survival time increases from 10.9 to 21.0 months when surgery is followed by adjuvant chemotherapy and radiation. This combination postoperatively does not increase mortality, but adds 30% morbidity. Photodynamic therapy has been demonstrated in preclinical studies to have a selective effect on malignant versus the normal pancreas. CONCLUSION: PDT is highly effective in eliciting the destruction of experimental pancreatic tumors with the lack of significant effect on the normal pancreas. The poor prognosis for patients with this disease, especially those patients with advanced disease, warrants closer examination of PDT for the treatment of pancreatic cancer.

Alterations in receptor-mediated kinases and phosphatases during carcinogenesis.

Increased phosphorylation in cancers can stimulate growth and up-regulate certain receptors. To test whether the functional response of phosphatase receptors is up-regulated during carcinogenesis, we examined the effects of ligands on net phosphorylation in isolated membranes derived from hamster cheek-pouch tissues undergoing malignant transformation. The buccal mucosa of groups of Syrian golden hamsters was exposed thrice weekly to 0.5% dimethylbenzanthracene (DMBA) in acetone for 2-12 weeks to produce premalignant and malignant tissues. Homogenates of these tissues were then incubated with [32P]ATP in the presence of epidermal growth factor (EGF), agonist of somatostatin analogue RC-160, luteinizing-hormone-releasing hormone (LH-RH) [D-Trp6]LH-RH, or combinations of EGF, RC-160, and [D-Trp6]LH-RH. Changes compared to controls in phosphorylation in response to ligands provided estimates of kinase or phosphatase activity. Phosphorylation increased continuously, from the first application of DMBA in a linear fashion, and independently of EGF stimulation. RC-160 and [D-Trp6]LH-RH reduced phosphorylation in vitro. This response occurred in premalignant (weeks 6-10 after DMBA application) as well as malignant tissues (week 12 after DMBA application), but was not significant in normal tissues. The results show a continuous augmentation in phosphatase activity prior to the appearance of cancers, but with a delay in expression following the primary event of increased kinase activity. Significantly less phosphorylation of substrates was induced by both RC-160 and [D-Trp6]LH-RH after in vitro activation by EGF than in the absence of EGF. This suggests that EGF activates latent systems of hormonal receptors. Collectively, these results support the hypothesis that the enhancement of the hormonally stimulated phosphatase in cancers occurs secondarily to the increased kinase activity.

Operation and intracavitary photodynamic therapy for malignant pleural mesothelioma: a phase II study.

From April 1991 to May 1993, 23 patients entered a phase II clinical study of surgical resection and adjuvant intracavitary photodynamic therapy for malignant pleural mesothelioma. Two days preoperatively, patients received an intravenous injection of 2 mg/kg of the photosensitizer Photofrin. Six patients underwent a pleuro-pneumonectomy, and 15 patients a pleurectomy, after which intracavitary photodynamic therapy was administered. A total light energy dose of 20 to 25 J/cm2 was given. In 2 patients the tumor was unresectable due to intrapericardial invasion. Postoperative complications were noted in more than 50 percent of patients; 2 patients died of postoperative complications. Postoperative survival was analyzed according to intraoperative staging proposed by the American Joint Committee for Cancer Staging, published in 1992. The overall estimated median survival is 12 months; that of stage III and IV patients is 7 months. Five patients with stage I and II diseases (who had grossly complete resection by pleurectomy) are alive, disease-free, for 11, 17, 18, 21, and 33 postoperative months. Intraoperative staging is important in carrying out further clinical studies of malignant pleural mesothelioma.

Synergistic effects of bombesin and epidermal growth factor on cancers.

Bombesin and gastrin-releasing peptide act as autocrine mitogens in various cancers. Bombesin antagonist RC-3095 inhibited growth in some cancers and slowed the progression of premalignant lesions, possibly by down-regulating epidermal growth factor (EGF) receptors. Since the EGF receptor mitogen response involves tyrosine kinase stimulation, we tested the hypotheses that bombesin stimulates, and RC-3095 inhibits, phosphorylation; EGF and bombesin promote the phosphorylation of the same substrates; and EGF and bombesin act synergistically on phosphorylation. Therefore, in vitro assays for phosphorylation were performed in the presence or absence of EGF, bombesin, RC-3095, and combinations in samples derived from tumor, tissue surrounding tumor, cell lines, and normal and transforming tissue derived from the 9,10-dimethyl-1,2-benzanthracene-induced squamous cell lesions of the hamster cheek pouch. Bombesin increased, and RC-3095 decreased, phosphorylation in these samples. In the human hepatoma sample and surrounding tissue, these ligands altered the phosphorylation of the same substrates affected by EGF. EGF and bombesin stimulated phosphorylation synergistically in the hamster samples and the hepatoma. Bombesin-induced phosphorylation was greater in tissue surrounding the hepatoma, whereas RC-3095 was more effective in inhibiting phosphorylation in the hepatoma itself. This cancer, therefore, could be endogenously stimulated by gastrin-releasing peptide. These observations support the hypothesis that bombesin stimulates growth of tissues and tumors by amplifying the phosphorylation response to EGF. The growth inhibitory response to RC-3095, or other bombesin analogues, of individual tumors may be prognosed by in vitro phosphorylation assays using the samples from the patient's tumor.

Evaluation of porfimer sodium fluorescence for measuring tissue transformation.

BACKGROUND: Neoplastic tissue can be detected by its increased fluorescence compared with surrounding normal tissue after the injection of the tumor-localizing compound porfimer sodium (Photofrin; Quadra Logic Technologies, Vancouver, BC, Canada). In vivo fluorescence photometry is a nonimaging photodetector technique that detects specific 690 nm fluorescence of the porphyrin by subtracting nonspecific 612 nm excitation from 630 nm excitation. The technique was applied in the developmental stages of the 9,10 dimethyl-1,2-benzanthracene (DMBA)-induced hamster buccal cheek pouch carcinoma model to (1) quantitate and characterize porfimer sodium fluorescence and uptake as it relates to lesion progression and biochemical changes and (2) determine whether porfimer sodium-induced fluorescence will vary with promotional and inhibitory stimuli. METHODS: Groups of Syrian Golden hamsters had their cheek pouch buccal mucosa exposed to a 0.5% DMBA in acetone three times per week for 6 weeks (premalignant lesions), 12 weeks (squamous cell carcinomas), or other specified durations. The rate of malignant transformation was either promoted (by either carbon dioxide laser incision or continued DMBA application) or inhibited (by the administration of either somatostatin analogue RC-160 [D-Phe-Cys-Tyr-D-Trp-Lys-Val-Cys-Trp-NH2] or bombesin antagonist RC-3095 [D-Tpi-Gln-Trp-Ala-Val-Gly-His-Leu psi (CH2NH)Leu-NH2]). Groups of DMBA-exposed hamsters were subsequently injected with 1.0 mg/kg of porfimer sodium during the various stages of tumor development. Twenty-four hours after injection, fluorescence levels were measured by in vivo fluorescence photometry. Samples of tumors, dysplastic mucosal tissue, and normal-appearing oral mucosa were biopsied and used for either tissue extraction assays, histopathologic examination, or tyrosine kinase activity assay as an index of rate of transformation. RESULTS: Results demonstrated that porfimer sodium is retained in DMBA-treated tissue. Fluorescence is completely accounted for by porfimer sodium uptake. The duration of exposure to carcinogen is proportional to porfimer sodium fluorescence. This relationship establishes that premalignant lesions can be distinguished from normal tissue by porfimer sodium uptake and fluorescence. The changes in increased tyrosine kinase activity paralleled the increase in porfimer sodium fluorescence. Alterations in the rate of tissue transformation produced equivalent alterations in porfimer sodium-induced fluorescence. CONCLUSIONS: These results suggest that porfimer sodium uptake and fluorescence can be used in a prognostic manner to diagnose and determine the course of transformation of individual lesions.